JP7054633B2 - Electron microscope and electron microscope control method - Google Patents

Electron microscope and electron microscope control method Download PDF

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JP7054633B2
JP7054633B2 JP2018022129A JP2018022129A JP7054633B2 JP 7054633 B2 JP7054633 B2 JP 7054633B2 JP 2018022129 A JP2018022129 A JP 2018022129A JP 2018022129 A JP2018022129 A JP 2018022129A JP 7054633 B2 JP7054633 B2 JP 7054633B2
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琢磨 岩崎
祐二 河野
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Jeol Ltd
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Description

本発明は、電子顕微鏡および電子顕微鏡の制御方法に関する。 The present invention relates to an electron microscope and a control method for the electron microscope.

電子顕微鏡に搭載されている電子銃は、エミッタと、エミッタから電子を引き出す引き出し電極と、エミッタから放出された電子線に所定のエネルギーを与える加速電極と、を備えている。また、電子銃から放出された電子線は加速管で加速される。加速管は複数の加速電極を有しており、各加速電極には、加速電圧を複数段の分圧用抵抗で分圧した電圧が印加される。 The electron gun mounted on the electron microscope includes an emitter, a drawing electrode that draws electrons from the emitter, and an accelerating electrode that gives a predetermined energy to the electron beam emitted from the emitter. In addition, the electron beam emitted from the electron gun is accelerated by the acceleration tube. The accelerating tube has a plurality of accelerating electrodes, and a voltage obtained by dividing the accelerating voltage by a plurality of stages of voltage dividing resistors is applied to each accelerating electrode.

電子顕微鏡では、引き出し電極と加速電極との間のレンズ作用、および加速電極と加速管の初段の加速電極との間のレンズ作用によって、加速管の下にクロスオーバーを形成している。 In the electron microscope, a crossover is formed under the accelerating tube by the lens action between the extraction electrode and the accelerating electrode and the lens action between the accelerating electrode and the first-stage accelerating electrode of the accelerating tube.

ここで、例えば、加速電圧を高加速電圧から低加速電圧に切り替えた場合、これらのレンズ条件が成り立たなくなる。そのため、特許文献１には、分圧用抵抗に並列にそれぞれの端子とアース間を短絡する段数切り替えスイッチを設けて、加速電圧の変更に応じて、分圧用抵抗の段数を切り替えている。 Here, for example, when the acceleration voltage is switched from the high acceleration voltage to the low acceleration voltage, these lens conditions do not hold. Therefore, in Patent Document 1, a stage number changeover switch for short-circuiting between each terminal and the ground is provided in parallel with the voltage division resistance, and the number of stages of the voltage division resistance is switched according to the change of the acceleration voltage.

特開平５－２９０７７４号公報Japanese Unexamined Patent Publication No. 5-290774

しかしながら、特許文献１に記載の電子顕微鏡では、段数切り替えスイッチを操作する際には、加速電圧の印加を停止しなければならない。加速電圧の印加を停止してしまうと、再び加速電圧が印加されて電子銃が安定するまでには時間がかかってしまう。 However, in the electron microscope described in Patent Document 1, the application of the acceleration voltage must be stopped when the stage number changeover switch is operated. If the application of the acceleration voltage is stopped, it will take time for the electron gun to stabilize by applying the acceleration voltage again.

本発明に係る電子顕微鏡の一態様は、
エミッタと、
前記エミッタから電子を引き出す引き出し電極と、
前記引き出し電極の後段に配置され、前記エミッタから引き出された電子線を加速させる第１加速電極と、
前記第１加速電極の後段に配置され、複数の第２加速電極を備える加速管と、
加速電圧を発生させる加速電圧電源と、
前記第１加速電極に電圧を印加する加速電極用電源と、
補助電圧を発生させる補助電圧電源と、
前記加速電圧と前記補助電圧とが重畳された入力電圧を分圧して、前記複数の第２加速電極の各々に印加する複数の分圧用抵抗と、
を含み、
前記加速電極用電源で前記第１加速電極の電位を制御し、前記補助電圧電源で前記複数の第２加速電極のうちの１つの第２加速電極の電位を制御することによって、前記第１加速電極と前記１つの第２加速電極との間のレンズ作用を制御する。 One aspect of the electron microscope according to the present invention is
Emitter and
An extraction electrode that draws electrons from the emitter and
A first accelerating electrode, which is arranged after the extraction electrode and accelerates the electron beam drawn from the emitter,
An accelerating tube arranged after the first accelerating electrode and having a plurality of second accelerating electrodes,
Acceleration voltage power supply that generates acceleration voltage,
A power supply for an accelerating electrode that applies a voltage to the first accelerating electrode,
Auxiliary voltage power supply that generates auxiliary voltage and
A plurality of voltage dividing resistors that divide the input voltage on which the acceleration voltage and the auxiliary voltage are superimposed and apply it to each of the plurality of second acceleration electrodes.
Including
The first acceleration is performed by controlling the potential of the first acceleration electrode with the power supply for the acceleration electrode and controlling the potential of the second acceleration electrode of one of the plurality of second acceleration electrodes with the auxiliary voltage power supply. It controls the lens action between the electrode and the one second acceleration electrode .

このような電子顕微鏡では、複数の分圧用抵抗の入力電圧を、加速電圧と補助電圧とが重畳された電圧とすることができるため、補助電圧を制御することによって、第１加速電極と初段の第２加速電極との間の電位差を制御することができる。これにより、第１加速電極と初段の第２加速電極との間に形成されるレンズの作用を制御できる。そのため、このような電子顕微鏡では、加速電圧が変更された場合であっても、加速電圧の印加を停止
することなく、第１加速電極と初段の第２加速電極との間に形成されるレンズの作用が低下することを抑制できる。 In such an electron microscope, the input voltage of a plurality of voltage dividing resistors can be a voltage obtained by superimposing an acceleration voltage and an auxiliary voltage. Therefore, by controlling the auxiliary voltage, the first acceleration electrode and the first stage can be used. The potential difference with the second acceleration electrode can be controlled. Thereby, the action of the lens formed between the first accelerating electrode and the second accelerating electrode of the first stage can be controlled. Therefore, in such an electron microscope, a lens formed between the first acceleration electrode and the second acceleration electrode of the first stage without stopping the application of the acceleration voltage even when the acceleration voltage is changed. It is possible to suppress the decrease in the action of.

本発明に係る電子顕微鏡の制御方法の一態様は、
エミッタと、
前記エミッタから電子を引き出す引き出し電極と、
前記引き出し電極の後段に配置され、前記エミッタから引き出された電子線を加速させる第１加速電極と、
前記第１加速電極の後段に配置され、複数の第２加速電極を備える加速管と、
加速電圧を発生させる加速電圧電源と、
前記引き出し電極に電圧を印加する引き出し電極用電源と、
前記第１加速電極に電圧を印加する加速電極用電源と、
補助電圧を発生させる補助電圧電源と、
前記加速電圧と前記補助電圧とが重畳された入力電圧を分圧して前記複数の第２加速電極の各々に印加する複数の分圧用抵抗と、を含む電子顕微鏡の制御方法であって、
前記引き出し電極用電源で前記引き出し電極の電位を制御し、前記加速電極用電源で前記第１加速電極の電位を制御することによって、前記引き出し電極と前記第１加速電極の間のレンズ作用を制御する工程と、
前記加速電圧を変更する工程と、
前記加速電圧の変更に応じて前記補助電圧電源を制御することによって前記複数の第２加速電極のうちの１つの第２加速電極の電位を制御して、前記第１加速電極と前記１つの第２加速電極との間のレンズ作用を制御する工程と、
を含む。 One aspect of the electron microscope control method according to the present invention is
Emitter and
An extraction electrode that draws electrons from the emitter and
A first accelerating electrode, which is arranged after the extraction electrode and accelerates the electron beam drawn from the emitter,
An accelerating tube arranged after the first accelerating electrode and having a plurality of second accelerating electrodes,
Acceleration voltage power supply that generates acceleration voltage,
A power supply for the lead-out electrode that applies a voltage to the lead-out electrode,
A power supply for an accelerating electrode that applies a voltage to the first accelerating electrode,
Auxiliary voltage power supply that generates auxiliary voltage and
It is a control method of an electron microscope including a plurality of voltage dividing resistors that divide an input voltage in which the acceleration voltage and the auxiliary voltage are superimposed and apply it to each of the plurality of second acceleration electrodes.
By controlling the potential of the extraction electrode with the power supply for the extraction electrode and controlling the potential of the first acceleration electrode with the power supply for the acceleration electrode, the lens action between the extraction electrode and the first acceleration electrode is controlled. And the process to do
The process of changing the acceleration voltage and
By controlling the auxiliary voltage power supply in response to the change in the acceleration voltage, the potential of the second acceleration electrode of the plurality of second acceleration electrodes is controlled, and the first acceleration electrode and the first acceleration electrode are controlled. 2 The process of controlling the lens action between the accelerating electrode and
Including .

このような電子顕微鏡の制御方法では、加速電圧の変更に応じて補助電圧を設定し、加速電圧に補助電圧を重畳して入力電圧とする工程を含むため、加速電圧が変更された場合であっても、加速電圧の印加を停止することなく、第１加速電極と初段の第２加速電極との間に形成されるレンズの作用が低下することを抑制できる。 Such an electronic microscope control method includes a step of setting an auxiliary voltage according to a change in the acceleration voltage and superimposing the auxiliary voltage on the acceleration voltage to obtain an input voltage, so that the acceleration voltage may be changed. However, it is possible to suppress a decrease in the action of the lens formed between the first acceleration electrode and the second acceleration electrode of the first stage without stopping the application of the acceleration voltage.

実施形態に係る電子顕微鏡の構成を示す図。The figure which shows the structure of the electron microscope which concerns on embodiment. 実施形態に係る電子顕微鏡の電子銃および加速管の構成を示す図。The figure which shows the structure of the electron gun and the acceleration tube of the electron microscope which concerns on embodiment. 実施形態に係る電子顕微鏡の電子銃および加速管の動作状態を示す図。The figure which shows the operation state of the electron gun and the acceleration tube of the electron microscope which concerns on embodiment. 参考例に係る電子顕微鏡の電子銃および加速管の動作状態を示す図。The figure which shows the operation state of the electron gun and the acceleration tube of the electron microscope which concerns on a reference example. 参考例に係る電子顕微鏡の電子銃および加速管の動作状態を示す図。The figure which shows the operation state of the electron gun and the acceleration tube of the electron microscope which concerns on a reference example.

以下、本発明の好適な実施形態について図面を用いて詳細に説明する。なお、以下に説明する実施形態は、特許請求の範囲に記載された本発明の内容を不当に限定するものではない。また、以下で説明される構成の全てが本発明の必須構成要件であるとは限らない。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unreasonably limit the content of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

１． 電子顕微鏡
まず、本実施形態に係る電子顕微鏡について図面を参照しながら説明する。図１は、本実施形態に係る電子顕微鏡１の構成を示す図である。 1. 1. Electron Microscope First, the electron microscope according to this embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electron microscope 1 according to the present embodiment.

電子顕微鏡１は、図１に示すように、電子銃１０と、加速管２０と、電源部３０と、制御部３２と、収束レンズ４０と、試料ホルダー５０と、対物レンズ６０と、中間レンズ７０と、投影レンズ８０と、検出器９０と、を含む。 As shown in FIG. 1, the electron microscope 1 includes an electron gun 10, an acceleration tube 20, a power supply unit 30, a control unit 32, a focusing lens 40, a sample holder 50, an objective lens 60, and an intermediate lens 70. The projection lens 80 and the detector 90 are included.

電子顕微鏡１では、電子銃１０から放出された電子線を、加速管２０で加速し収束レンズ４０で収束して試料ホルダー５０に保持された試料Ｓに照射する。そして、対物レンズ６０によって試料Ｓを透過した電子線で透過電子顕微鏡像を結像し、中間レンズ７０および投影レンズ８０によって像をさらに拡大して検出器９０上に結像する。電子銃１０および加速管２０には、電源部３０から加速電圧等が供給される。電源部３０は、制御部３２によって制御される。このように、電子顕微鏡１は、透過電子顕微鏡（transmission electron microscope、ＴＥＭ）である。 In the electron microscope 1, the electron beam emitted from the electron gun 10 is accelerated by the accelerating tube 20 and converged by the focusing lens 40 to irradiate the sample S held in the sample holder 50. Then, a transmission electron microscope image is formed by the electron beam transmitted through the sample S by the objective lens 60, and the image is further magnified by the intermediate lens 70 and the projection lens 80 to form an image on the detector 90. Acceleration voltage and the like are supplied from the power supply unit 30 to the electron gun 10 and the acceleration tube 20. The power supply unit 30 is controlled by the control unit 32. As described above, the electron microscope 1 is a transmission electron microscope (TEM).

なお、電子顕微鏡１は、図示はしないが、試料Ｓに照射される電子線を走査する走査コイルを備え、走査透過電子顕微鏡像を取得できるように構成されていてもよい。すなわち、電子顕微鏡１は、走査透過電子顕微鏡（scanning transmission electron microscope、ＳＴＥＭ）として機能してもよい。 Although not shown, the electron microscope 1 may be provided with a scanning coil for scanning the electron beam irradiated to the sample S so that a scanning transmission electron microscope image can be obtained. That is, the electron microscope 1 may function as a scanning transmission electron microscope (STEM).

図２は、電子銃１０および加速管２０の構成を示す図である。 FIG. 2 is a diagram showing the configuration of the electron gun 10 and the acceleration tube 20.

電子銃１０は、図２に示すように、エミッタ１００と、引き出し電極１０２と、加速電極（第１加速電極）１０４と、を含む。 As shown in FIG. 2, the electron gun 10 includes an emitter 100, a pull-out electrode 102, and an accelerating electrode (first accelerating electrode) 104.

エミッタ１００（フィラメント）は、電子の放出源、すなわち陰極である。エミッタ１００は、フィラメント電源３０１に接続されている。エミッタ１００には、フィラメント電源３０１からフィラメント電流が供給される。エミッタ１００にフィラメント電流を流すことによって、エミッタ１００が加熱される。 The emitter 100 (filament) is a source of electrons, that is, a cathode. The emitter 100 is connected to the filament power supply 301. A filament current is supplied to the emitter 100 from the filament power supply 301. The emitter 100 is heated by passing a filament current through the emitter 100.

引き出し電極１０２は、エミッタ１００から電子を引き出すための電極である。引き出し電極１０２は、エミッタ１００に対向して配置されている。引き出し電極１０２は、引き出し電極用電源３０２に接続されている。引き出し電極１０２には、エミッタ１００の表面に強電界を形成するための正の電圧（引き出し電圧）が印加される。 The extraction electrode 102 is an electrode for extracting electrons from the emitter 100. The extraction electrode 102 is arranged so as to face the emitter 100. The extraction electrode 102 is connected to a power supply 302 for the extraction electrode. A positive voltage (pull-out voltage) for forming a strong electric field on the surface of the emitter 100 is applied to the lead-out electrode 102.

加速電極１０４は、引き出し電極１０２の後段に配置されている。加速電極１０４は、エミッタ１００から放出される電子線に所定のエネルギーを与えるための電極である。加速電極１０４は、加速電極用電源３０４に接続されている。 The acceleration electrode 104 is arranged after the extraction electrode 102. The accelerating electrode 104 is an electrode for applying a predetermined energy to the electron beam emitted from the emitter 100. The accelerating electrode 104 is connected to the accelerating electrode power supply 304.

加速管２０は、複数の加速電極（第２加速電極）２０１，２０２，２０３，２０４，２０５，２０６と、碍子２１０と、複数の分圧用抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７を有する分圧用回路２２０と、筐体２３０と、を含む。 The accelerating tube 20 includes a plurality of accelerating electrodes (second accelerating electrodes) 201, 202, 203, 204, 205, 206, an insulator 210, and a plurality of voltage dividing resistance elements 221,222, 223, 224, 225, 226. A voltage dividing circuit 220 having 227 and a housing 230 are included.

加速電極２０１，２０２，２０３，２０４，２０５，２０６は、加速電極１０４の後段に配置されている。加速電極２０１，２０２，２０３，２０４，２０５，２０６は、光軸に沿って複数段に積み重ねられている。図示の例では、加速管２０は、６段の加速電極２０１，２０２，２０３，２０４，２０５，２０６を有している。これらは、電子銃１０側から、加速電極２０１、加速電極２０２、加速電極２０３、加速電極２０４、加速電極２０５、加速電極２０６の順で配置されている。隣り合う加速電極の間には、碍子２１０が配置されている。複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６によって、電子銃１０から放出された電子線を加速させることができる。 The accelerating electrodes 201, 202, 203, 204, 205, 206 are arranged after the accelerating electrode 104. The acceleration electrodes 201, 202, 203, 204, 205, 206 are stacked in a plurality of stages along the optical axis. In the illustrated example, the accelerating tube 20 has six stages of accelerating electrodes 201, 202, 203, 204, 205, 206. These are arranged in the order of the accelerating electrode 201, the accelerating electrode 202, the accelerating electrode 203, the accelerating electrode 204, the accelerating electrode 205, and the accelerating electrode 206 from the electron gun 10 side. Insulator 210s are arranged between adjacent acceleration electrodes. The electron beam emitted from the electron gun 10 can be accelerated by the plurality of acceleration electrodes 201, 202, 203, 204, 205, 206.

加速電極２０１は、加速管２０を構成する複数の加速電極のうちの初段の加速電極である。すなわち、加速電極２０３は、６段の加速電極のうちの最も電子銃１０側（加速電極１０４側）に位置している電極である。 The accelerating electrode 201 is the first-stage accelerating electrode among the plurality of accelerating electrodes constituting the accelerating tube 20. That is, the acceleration electrode 203 is an electrode located on the electron gun 10 side (acceleration electrode 104 side) of the six-stage acceleration electrodes.

分圧用回路２２０は、複数の抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７を有している。図示の例では、分圧用回路２２０は、７つの抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７を有している。７つの抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７は、直列に接続されている。 The voltage dividing circuit 220 has a plurality of resistance elements 221,222, 223, 224, 225, 226, 227. In the illustrated example, the voltage dividing circuit 220 has seven resistance elements 221,222, 223, 224, 225, 226, 227. The seven resistance elements 221,222,223,224,225,226,227 are connected in series.

電子顕微鏡１では、分圧用回路２２０に印加される入力電圧、すなわち、複数の抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７の全体に印加される入力電圧を、高圧電源３００が発生させる加速電圧と、補助電圧電源３０６が発生させる補助電圧と、が重畳された電圧とすることができる。分圧用回路２２０では、入力電圧を複数の
抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７で分圧して、複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６の各々に印加する。 In the electron microscope 1, the high-voltage power supply 300 generates an input voltage applied to the voltage dividing circuit 220, that is, an input voltage applied to the entire plurality of resistance elements 221,222, 223, 224, 225, 226, 227. The accelerating voltage to be generated and the auxiliary voltage generated by the auxiliary voltage power supply 306 can be superimposed. In the voltage dividing circuit 220, the input voltage is divided by a plurality of resistance elements 221,222,223,224,225,226,227 and applied to each of the plurality of accelerating electrodes 201, 202, 203, 204, 205, 206. do.

筐体２３０には電子線が入射する開口が設けられており、電子線は当該開口を通過して筐体２３０の内部に至る。筐体２３０には、複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６が収容されている。筐体２３０の電子線が入射する開口が設けられた入口部分２３２は、高圧電源３００に接続されている。 The housing 230 is provided with an opening through which the electron beam is incident, and the electron beam passes through the opening and reaches the inside of the housing 230. A plurality of acceleration electrodes 201, 202, 203, 204, 205, 206 are housed in the housing 230. The inlet portion 232 provided with an opening through which the electron beam of the housing 230 is incident is connected to the high voltage power supply 300.

電源部３０は、高圧電源３００（加速電圧電源）と、フィラメント電源３０１と、引き出し電極用電源３０２と、加速電極用電源３０４と、補助電圧電源３０６と、を含む。 The power supply unit 30 includes a high voltage power supply 300 (acceleration voltage power supply), a filament power supply 301, a lead-out electrode power supply 302, an acceleration electrode power supply 304, and an auxiliary voltage power supply 306.

高圧電源３００は、エミッタ１００で発生した電子線を加速させるための加速電圧を供給する。加速電圧は、エミッタ１００と加速管２０との間に印加される。電子顕微鏡１では、加速電圧は可変である。 The high voltage power supply 300 supplies an acceleration voltage for accelerating the electron beam generated by the emitter 100. The acceleration voltage is applied between the emitter 100 and the accelerating tube 20. In the electron microscope 1, the acceleration voltage is variable.

フィラメント電源３０１は、エミッタ１００にフィラメント電流を供給する。 The filament power supply 301 supplies a filament current to the emitter 100.

引き出し電極用電源３０２は、引き出し電極１０２に引き出し電圧（正の電圧）を印加する。引き出し電圧は、エミッタ１００から電子線を引き出すために引き出し電極１０２に印加される電圧である。 The lead-out electrode power supply 302 applies a lead-out voltage (positive voltage) to the lead-out electrode 102. The extraction voltage is a voltage applied to the extraction electrode 102 to extract an electron beam from the emitter 100.

加速電極用電源３０４は、加速電極１０４に正の電圧を供給する。 The power supply 304 for the accelerating electrode supplies a positive voltage to the accelerating electrode 104.

補助電圧電源３０６は、高圧電源３００と初段の抵抗素子２２１との間に配置されている。補助電圧電源３０６は、補助電圧を発生させる。補助電圧電源３０６は、高圧電源３００に直列に接続されている。補助電圧電源３０６は、高圧電源３００が発生させる加速電圧に補助電圧を重畳して分圧用回路２２０に印加する。これにより、分圧用回路２２０に印加される入力電圧を、高圧電源３００が発生させる加速電圧と補助電圧電源３０６が発生させる補助電圧が重畳された電圧とすることができる。補助電圧電源３０６が発生させる補助電圧は、可変である。 The auxiliary voltage power supply 306 is arranged between the high voltage power supply 300 and the resistance element 221 of the first stage. The auxiliary voltage power supply 306 generates an auxiliary voltage. The auxiliary voltage power supply 306 is connected in series with the high voltage power supply 300. The auxiliary voltage power supply 306 superimposes the auxiliary voltage on the acceleration voltage generated by the high voltage power supply 300 and applies it to the voltage dividing circuit 220. As a result, the input voltage applied to the voltage dividing circuit 220 can be a voltage obtained by superimposing the acceleration voltage generated by the high voltage power supply 300 and the auxiliary voltage generated by the auxiliary voltage power supply 306. Auxiliary voltage The auxiliary voltage generated by the power supply 306 is variable.

なお、図示はしないが、電子顕微鏡１は、高圧電源３００を補助電圧電源３０６を介して分圧用回路２２０に接続する場合と、高圧電源３００を補助電圧電源３０６を介さずに直接、分圧用回路２２０に接続する場合と、を切り替える手段（スイッチ）を有していてもよい。これにより、分圧用回路２２０に加速電圧と補助電圧とを重畳して印加する場合と、分圧用回路２２０に加速電圧のみを印加する場合と、を切り替えることができる。 Although not shown, the electron microscope 1 has a case where the high voltage power supply 300 is connected to the voltage dividing circuit 220 via the auxiliary voltage power supply 306 and a case where the high voltage power supply 300 is directly connected to the voltage dividing circuit 220 without the auxiliary voltage power supply 306. It may have a means (switch) for switching between the case of connecting to 220 and the case of connecting to 220. Thereby, it is possible to switch between the case where the acceleration voltage and the auxiliary voltage are superimposed and applied to the voltage dividing circuit 220 and the case where only the acceleration voltage is applied to the voltage dividing circuit 220.

引き出し電極用電源３０２、加速電極用電源３０４、補助電圧電源３０６は、高圧電源３００の出力電圧を基準電位としている。 The lead-out electrode power supply 302, the acceleration electrode power supply 304, and the auxiliary voltage power supply 306 use the output voltage of the high-voltage power supply 300 as a reference potential.

図１に示す制御部３２は、高圧電源３００、フィラメント電源３０１、引き出し電極用電源３０２、加速電極用電源３０４、および補助電圧電源３０６を制御する。制御部３２の機能は、各種プロセッサ（ＣＰＵ（Central Processing Unit）等）でプログラムを実行することにより実現することができる。なお、制御部３２の機能の少なくとも一部を、ＡＳＩＣ（application specific integrated circuit）などの専用回路により実現してもよい。制御部３２の処理については、後述する「３． 制御部の処理」で説明する。 The control unit 32 shown in FIG. 1 controls a high-voltage power supply 300, a filament power supply 301, a power supply 302 for an extraction electrode, a power supply 304 for an acceleration electrode, and an auxiliary voltage power supply 306. The function of the control unit 32 can be realized by executing a program on various processors (CPU (Central Processing Unit) or the like). At least a part of the function of the control unit 32 may be realized by a dedicated circuit such as an ASIC (application specific integrated circuit). The processing of the control unit 32 will be described in "3. Processing of the control unit" described later.

２． 電子顕微鏡の動作
次に、電子顕微鏡１の動作について説明する。まず、電子顕微鏡１の電子銃１０および加速管２０の基本的な動作について説明する。 2. 2. Operation of the electron microscope Next, the operation of the electron microscope 1 will be described. First, the basic operations of the electron gun 10 and the acceleration tube 20 of the electron microscope 1 will be described.

電子顕微鏡１では、引き出し電極１０２に引き出し電極用電源３０２が発生させる正の電圧が印加されることによって、エミッタ１００から電子が引き出される。そして、加速電極１０４には加速電極用電源３０４が発生させる正の電圧が印加され、引き出し電極１０２と加速電極１０４との間には、引き出し電極１０２と加速電極１０４とによって形成される電界により収束レンズ（静電レンズ）が形成される。 In the electron microscope 1, electrons are extracted from the emitter 100 by applying a positive voltage generated by the power supply 302 for the extraction electrode to the extraction electrode 102. Then, a positive voltage generated by the power supply 304 for the accelerating electrode is applied to the accelerating electrode 104, and the electric field formed between the extraction electrode 102 and the accelerating electrode 104 converges between the extraction electrode 102 and the accelerating electrode 104. A lens (electrostatic lens) is formed.

また、分圧用回路２２０には、高圧電源３００が発生させる加速電圧と、補助電圧電源３０６が発生させる補助電圧とが重畳された入力電圧が印加される。これにより、当該入力電圧が分圧されて、複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６の各々に印加される。加速電極１０４と初段の加速電極２０１との間には、加速電極１０４と初段の加速電極２０１とによって形成される電界により収束レンズ（静電レンズ）が形成される。 Further, an input voltage in which the acceleration voltage generated by the high voltage power supply 300 and the auxiliary voltage generated by the auxiliary voltage power supply 306 are superimposed is applied to the voltage dividing circuit 220. As a result, the input voltage is divided and applied to each of the plurality of acceleration electrodes 201, 202, 203, 204, 205, 206. A convergent lens (electrostatic lens) is formed between the accelerating electrode 104 and the first-stage accelerating electrode 201 by the electric field formed by the accelerating electrode 104 and the first-stage accelerating electrode 201.

このように、エミッタ１００から引き出された電子は、引き出し電極１０２と加速電極１０４との間に形成される収束レンズの作用、および加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用によって、加速管２０の下にクロスオーバーを形成する。 In this way, the electrons drawn from the emitter 100 are the action of the focusing lens formed between the extraction electrode 102 and the accelerating electrode 104, and the convergence formed between the accelerating electrode 104 and the first-stage accelerating electrode 201. By the action of the lens, a crossover is formed under the acceleration tube 20.

次に、引き出し電極１０２、加速電極１０４、および初段の加速電極２０１に印加される電圧について説明する。図３は、電子顕微鏡１の電子銃１０および加速管２０の動作状態を示す図である。下記表１は、加速電圧ＨＴ＝－２００ｋＶの場合と加速電圧ＨＴ＝－８０ｋＶの場合の、電圧Ａ１、電圧Ａ２、電圧Ａ３、および電位差Ａ２－Ａ３の一例を示す表である。なお、下記表１に示す電圧Ａ１、電圧Ａ２、および電圧Ａ３の値は一例であり、この値に限定されない。 Next, the voltage applied to the extraction electrode 102, the acceleration electrode 104, and the acceleration electrode 201 of the first stage will be described. FIG. 3 is a diagram showing an operating state of the electron gun 10 and the accelerating tube 20 of the electron microscope 1. Table 1 below shows an example of voltage A1, voltage A2, voltage A3, and potential difference A2-A3 when the acceleration voltage HT = −200 kV and the acceleration voltage HT = −80 kV. The values of voltage A1, voltage A2, and voltage A3 shown in Table 1 below are examples, and are not limited to these values.

Figure 0007054633000001
Figure 0007054633000001

図３に示すように、引き出し電極１０２には、引き出し電極用電源３０２が発生させる電圧Ａ１が印加される。加速電極１０４には、加速電極用電源３０４が発生させる電圧Ａ２が印加される。筐体２３０の入口部分２３２には高圧電源３００が発生させる加速電圧ＨＴが印加される。加速電極２０１には電圧Ａ３が印加される。 As shown in FIG. 3, a voltage A1 generated by the power supply 302 for the lead electrode is applied to the lead electrode 102. A voltage A2 generated by the power supply 304 for the accelerating electrode is applied to the accelerating electrode 104. An acceleration voltage HT generated by the high-voltage power supply 300 is applied to the inlet portion 232 of the housing 230. A voltage A3 is applied to the accelerating electrode 201.

まず、高加速電圧の場合について説明する。具体的には、高圧電源３００が発生させる加速電圧ＨＴがＨＴ＝－２００ｋＶである場合について説明する。 First, the case of a high acceleration voltage will be described. Specifically, a case where the acceleration voltage HT generated by the high-voltage power supply 300 is HT = −200 kV will be described.

加速電圧ＨＴ＝－２００ｋＶの場合、引き出し電極１０２には電圧Ａ１＝３ｋＶが印加され、加速電極１０４には電圧Ａ２＝６ｋＶが印加される。また、高加速電圧の場合、補助電圧電源３０６が発生させる補助電圧ＡＣＬは、０Ｖである。そのため、分圧用回路２２０には加速電圧ＨＴ＝－２００ｋＶのみが印加される。分圧用回路２２０の入力電圧（加速電圧ＨＴ＝－２００ｋＶ）は、７つの抵抗Ｒ１，Ｒ２，Ｒ３，Ｒ４，Ｒ５，Ｒ６，Ｒ７で分圧されて、電圧Ａ３＝－２００／７＝－２８．６ｋＶとなる。ここでは、７つの抵抗Ｒ１，Ｒ２，Ｒ３，Ｒ４，Ｒ５，Ｒ６，Ｒ７は互いに等しい抵抗値を有している。このように、電圧Ａ２は６ｋＶであり、電圧Ａ３は－２８．６ｋＶであるため、加速電極１０４と初段の加速電極２０１との間の電位差Ａ２－Ａ３は、２２．６ｋＶとなる。電位差Ａ２－Ａ３によって、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用の強弱が決まる。 When the acceleration voltage HT = −200 kV, the voltage A1 = 3 kV is applied to the extraction electrode 102 , and the voltage A2 = 6 kV is applied to the acceleration electrode 104. Further, in the case of a high acceleration voltage, the auxiliary voltage ACL generated by the auxiliary voltage power supply 306 is 0V. Therefore, only the acceleration voltage HT = −200 kV is applied to the voltage dividing circuit 220. The input voltage (acceleration voltage HT = -200 kV) of the voltage dividing circuit 220 is divided by seven resistors R1, R2, R3, R4, R5, R6, R7, and the voltage A3 = -200 / 7 = -28. It will be 6 kV. Here, the seven resistors R1, R2, R3, R4, R5, R6, and R7 have equal resistance values. As described above, since the voltage A2 is 6 kV and the voltage A3 is −28.6 kV, the potential difference A2-A3 between the accelerating electrode 104 and the accelerating electrode 201 of the first stage is 22.6 kV. The potential difference A2-A3 determines the strength of the action of the convergent lens formed between the acceleration electrode 104 and the acceleration electrode 201 of the first stage.

次に、低加速電圧の場合について説明する。具体的には、高圧電源３００が発生させる加速電圧ＨＴがＨＴ＝－８０ｋＶである場合について説明する。 Next, the case of a low acceleration voltage will be described. Specifically, a case where the acceleration voltage HT generated by the high-voltage power supply 300 is HT = −80 kV will be described.

加速電圧ＨＴ＝－８０ｋＶの場合、加速電圧ＨＴ＝－２００ｋＶの場合と同様に、引き出し電極１０２には電圧Ａ１＝３ｋＶが印加され、加速電極１０４には電圧Ａ２＝６ｋＶが印加される。低加速電圧の場合、補助電圧電源３０６が発生させる補助電圧ＡＣＬは、例えば、１０ｋＶである。そのため、分圧用回路２２０には加速電圧ＨＴ＝－８０ｋＶに補助電圧ＡＣＬ＝１０ｋＶが重畳された－７０ｋＶが印加される。したがって、電圧Ａ３＝－７０／７－１０＝－２０ｋＶとなる。よって、加速電極１０４と初段の加速電極２０１との間の電位差Ａ２－Ａ３は、１４ｋＶとなる。 When the acceleration voltage HT = −80 kV, the voltage A1 = 3 kV is applied to the extraction electrode 102 and the voltage A2 = 6 kV is applied to the acceleration electrode 104, as in the case of the acceleration voltage HT = −200 kV. In the case of a low acceleration voltage, the auxiliary voltage ACL generated by the auxiliary voltage power supply 306 is, for example, 10 kV. Therefore, −70 kV in which the auxiliary voltage ACL = 10 kV is superimposed on the acceleration voltage HT = −80 kV is applied to the voltage dividing circuit 220. Therefore, the voltage A3 = −70 / 7-10 = −20 kV. Therefore, the potential difference A2-A3 between the accelerating electrode 104 and the accelerating electrode 201 of the first stage is 14 kV.

このように、電子顕微鏡１では、低加速電圧の場合には、高加速電圧の場合と比べて、補助電圧ＡＣＬを大きくする。これにより、低加速電圧にすることによる初段の加速電極２０１の電位の低下を抑制でき、電位差Ａ２－Ａ３の低下が抑制される。この結果、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用の低下を抑制できる。 As described above, in the electron microscope 1, the auxiliary voltage ACL is increased in the case of the low acceleration voltage as compared with the case of the high acceleration voltage. As a result, the decrease in the potential of the acceleration electrode 201 in the first stage due to the low acceleration voltage can be suppressed, and the decrease in the potential difference A2-A3 is suppressed. As a result, it is possible to suppress a decrease in the action of the convergent lens formed between the accelerating electrode 104 and the first-stage accelerating electrode 201.

以下では、電子顕微鏡１と参考例に係る電子顕微鏡とを比較することで、電子顕微鏡１の作用効果を説明する。図４は、参考例に係る電子顕微鏡の電子銃１０および加速管２０の動作状態を示す図である。下記表２は、参考例に係る電子顕微鏡における加速電圧ＨＴ＝－２００ｋＶの場合と加速電圧ＨＴ＝－８０ｋＶの場合の、電圧Ａ１、電圧Ａ２、電圧Ａ３、および電位差Ａ２－Ａ３の一例を示す表である。 Hereinafter, the action and effect of the electron microscope 1 will be described by comparing the electron microscope 1 with the electron microscope according to the reference example. FIG. 4 is a diagram showing an operating state of the electron gun 10 and the accelerating tube 20 of the electron microscope according to the reference example. Table 2 below shows an example of voltage A1, voltage A2, voltage A3, and potential difference A2-A3 when the acceleration voltage HT = −200 kV and the acceleration voltage HT = -80 kV in the electron microscope according to the reference example. Is.

Figure 0007054633000002
Figure 0007054633000002

図４に示す例では、図２に示す補助電圧電源３０６がない。そのため、加速電圧ＨＴ＝－８０ｋＶの場合、分圧用回路２２０には加速電圧ＨＴ＝－８０ｋＶが印加される。したがって、初段の加速電極２０１に印加される電圧Ａ３は、電圧Ａ３＝－８０／７＝－１１．４ｋＶとなる。このように、図４に示す例では、低加速電圧とすることで、初段の加速電極２０１の電位が大きく低下してしまう。また、このとき、電圧Ａ１＝３ｋＶ、電圧Ａ２＝６ｋＶとすると、加速電極１０４と初段の加速電極２０１との間の電位差Ａ２－Ａ３は、５．４３ｋＶとなる。このように、図４に示す例では、初段の加速電極２０１の電位の低下により電位差Ａ２－Ａ３が低下し、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用が低下してしまう。この結果、電子線が拡がってしまい、所望の位置にクロスオーバーを形成できない場合がある。 In the example shown in FIG. 4, the auxiliary voltage power supply 306 shown in FIG. 2 is not provided. Therefore, when the acceleration voltage HT = −80 kV, the acceleration voltage HT = −80 kV is applied to the voltage dividing circuit 220. Therefore, the voltage A3 applied to the acceleration electrode 201 of the first stage is the voltage A3 = −80 / 7 = -11.4 kV. As described above, in the example shown in FIG. 4, the potential of the acceleration electrode 201 in the first stage is greatly reduced by setting the acceleration voltage to a low level. At this time, if the voltage A1 = 3 kV and the voltage A2 = 6 kV, the potential difference A2-A3 between the acceleration electrode 104 and the acceleration electrode 201 of the first stage is 5.43 kV. As described above, in the example shown in FIG. 4, the potential difference A2-A3 decreases due to the decrease in the potential of the acceleration electrode 201 in the first stage, and the action of the convergent lens formed between the acceleration electrode 104 and the acceleration electrode 201 in the first stage acts. It will drop. As a result, the electron beam may spread and the crossover may not be formed at a desired position.

また、例えば、図４に示す例では、電圧Ａ２を下げることで、電位差Ａ２－Ａ３を大きくすることができる。下記表３は、参考例に係る電子顕微鏡における加速電圧ＨＴ＝－２００ｋＶの場合と加速電圧ＨＴ＝－８０ｋＶの場合の、電圧Ａ１、電圧Ａ２、電圧Ａ３、および電位差Ａ２－Ａ３の他の例を示す表である。 Further, for example, in the example shown in FIG. 4, the potential difference A2-A3 can be increased by lowering the voltage A2. Table 3 below shows other examples of voltage A1, voltage A2, voltage A3, and potential difference A2-A3 when the acceleration voltage HT = −200 kV and the acceleration voltage HT = -80 kV in the electron microscope according to the reference example. It is a table showing.

Figure 0007054633000003
Figure 0007054633000003

例えば、加速電圧ＨＴ＝－８０ｋＶの場合に、電圧Ａ１＝３ｋＶ、電圧Ａ２＝３ｋＶとして、加速電圧ＨＴ＝－２００ｋＶの場合よりも電圧Ａ２を下げる。これにより、電位差Ａ２－Ａ３は８．４ｋＶとなり、電位差Ａ２－Ａ３の低下が抑制される。しかしながら、この場合、電圧Ａ２を下げたことにより、電位差Ａ１－Ａ２が小さくなり、引き出し電極１０２と加速電極１０４との間に形成される収束レンズの作用が低下してしまう。 For example, when the acceleration voltage HT = −80 kV, the voltage A1 = 3 kV and the voltage A2 = 3 kV, and the voltage A2 is lowered as compared with the case of the acceleration voltage HT = −200 kV. As a result, the potential difference A2-A3 becomes 8.4 kV, and the decrease in the potential difference A2-A3 is suppressed. However, in this case, by lowering the voltage A2, the potential difference A1-A2 becomes smaller, and the action of the convergent lens formed between the extraction electrode 102 and the acceleration electrode 104 is reduced.

図５は、参考例に係る電子顕微鏡の電子銃１０および加速管２０の動作状態を示す図である。下記表４は、参考例に係る電子顕微鏡における加速電圧ＨＴ＝－２００ｋＶの場合と加速電圧ＨＴ＝－８０ｋＶの場合の、電圧Ａ１、電圧Ａ２、電圧Ａ３、および電位差Ａ２－Ａ３の一例を示す表である。 FIG. 5 is a diagram showing an operating state of the electron gun 10 and the accelerating tube 20 of the electron microscope according to the reference example. Table 4 below shows an example of voltage A1, voltage A2, voltage A3, and potential difference A2-A3 when the acceleration voltage HT = −200 kV and the acceleration voltage HT = -80 kV in the electron microscope according to the reference example. Is.

Figure 0007054633000004
Figure 0007054633000004

図５に示す例では、低加速電圧にした場合に、３段目の加速電極２０３を、スイッチを用いて基準電位（例えば接地電位）に短絡させる短絡機構を備えている。この短絡機構により、加速電極２０１の電位の低下を抑制できる。例えば、図５に示すように、３段目の加速電極２０３を短絡させると、加速電極２０１に印加される電圧Ａ３は、電圧Ａ３＝－８０／３＝－２６．７ｋＶとなる。また、このとき、電位差Ａ２－Ａ３は、２０．７ｋＶとなる。このように、図５に示すように短絡機構を設けた場合、図４に示す例に比べて、電位差Ａ２－Ａ３の低下が抑制される。しかしながら、このような短絡機構を設けた場合、加速電極２０１を基準電位に短絡させる際には、加速電圧の印加を停止、すなわち、加速電圧を基準電位しなければならない。 The example shown in FIG. 5 is provided with a short-circuit mechanism for short-circuiting the third-stage acceleration electrode 203 to a reference potential (for example, a ground potential) using a switch when the acceleration voltage is low. By this short-circuit mechanism, it is possible to suppress a decrease in the potential of the accelerating electrode 201. For example, as shown in FIG. 5, when the acceleration electrode 203 of the third stage is short-circuited, the voltage A3 applied to the acceleration electrode 201 becomes the voltage A3 = −80 / 3 = −26.7 kV. At this time, the potential difference A2-A3 becomes 20.7 kV. As described above, when the short-circuit mechanism is provided as shown in FIG. 5, the decrease in the potential difference A2-A3 is suppressed as compared with the example shown in FIG. However, when such a short-circuit mechanism is provided, when the acceleration electrode 201 is short-circuited to the reference potential, the application of the acceleration voltage must be stopped, that is, the acceleration voltage must be set to the reference potential.

これに対して、電子顕微鏡１では、補助電圧ＡＣＬを変更することによって、加速電極２０１の電位を制御できるため、加速電圧ＨＴが変更された場合であっても、加速電圧ＨＴの印加を停止することなく、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用が低下することを抑制できる。 On the other hand, in the electron microscope 1, since the potential of the acceleration electrode 201 can be controlled by changing the auxiliary voltage ACL, the application of the acceleration voltage HT is stopped even when the acceleration voltage HT is changed. Without this, it is possible to suppress a decrease in the action of the convergent lens formed between the acceleration electrode 104 and the acceleration electrode 201 of the first stage.

さらに、電子顕微鏡１では、補助電圧ＡＣＬが可変であり、加速電極２０１の電位を細かく制御することができる。そのため、例えば、上記の短絡機構を用いた場合と比べて、電位差Ａ２－Ａ３を細かく制御することが可能である。例えば、上記の短絡機構を用いた場合、電圧Ａ３は加速電圧と抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７の数で決定されるため、電位差Ａ２－Ａ３の細かい制御はできない。 Further, in the electron microscope 1, the auxiliary voltage ACL is variable, and the potential of the accelerating electrode 201 can be finely controlled. Therefore, for example, the potential difference A2-A3 can be finely controlled as compared with the case where the above-mentioned short-circuit mechanism is used. For example, when the above short-circuit mechanism is used, the voltage A3 is determined by the acceleration voltage and the number of resistance elements 221,222,223,224,225,226,227, so that the potential difference A2-A3 cannot be finely controlled.

３． 制御部の処理
次に、制御部３２の処理について説明する。 3. 3. Processing of the control unit Next, the processing of the control unit 32 will be described.

制御部３２は、加速電圧ＨＴを変更する処理と、加速電圧ＨＴの変更に応じて補助電圧ＡＣＬを設定し、加速電圧ＨＴに補助電圧ＡＣＬを重畳して分圧用回路２２０の入力電圧とする処理と、を行う。 The control unit 32 has a process of changing the acceleration voltage HT and a process of setting an auxiliary voltage ACL according to the change of the acceleration voltage HT and superimposing the auxiliary voltage ACL on the acceleration voltage HT to obtain the input voltage of the voltage dividing circuit 220. And do.

制御部３２は、加速電圧が高加速電圧から低加速電圧に変更された場合、低加速電圧に切り替えたことによる初段の加速電極２０１の電位の低下が抑制されるように補助電圧ＡＣＬを設定する。 The control unit 32 sets the auxiliary voltage ACL so that when the acceleration voltage is changed from the high acceleration voltage to the low acceleration voltage, the decrease in the potential of the acceleration electrode 201 in the first stage due to the switching to the low acceleration voltage is suppressed. ..

例えば、加速電圧ＨＴ＝－２００ｋＶの場合、制御部３２は、電圧Ａ１＝３ｋＶ、電圧Ａ２＝６ｋＶ、補助電圧ＡＣＬ＝０ｋＶとなるように電源部３０を制御する。このとき、電圧Ａ３＝－２００／７＝－２８．６ｋＶとなり、電位差Ａ２－Ａ３＝２２．６ｋＶとなる。 For example, when the acceleration voltage HT = −200 kV, the control unit 32 controls the power supply unit 30 so that the voltage A1 = 3 kV, the voltage A2 = 6 kV, and the auxiliary voltage ACL = 0 kV. At this time, the voltage A3 = −200 / 7 = −28.6 kV, and the potential difference A2-A3 = 22.6 kV.

加速電圧ＨＴ＝－２００ｋＶから加速電圧ＨＴ＝－８０ｋＶに切り替えた場合、制御部３２は、電圧Ａ１＝３ｋＶ、電圧Ａ２＝６ｋＶ、補助電圧ＡＣＬ＝１０ｋＶとなるように電源部３０を制御する。このとき、電圧Ａ３＝－７０／７＋１０＝－２０ｋＶとなり、電位差Ａ２－Ａ３＝１４ｋＶとなる。このように、制御部３２の処理により、低加速電圧に切り替えたことによる初段の加速電極２０１の電位の低下が抑制され、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用の低下を抑制できる。 When the acceleration voltage HT = −200 kV is switched to the acceleration voltage HT = −80 kV, the control unit 32 controls the power supply unit 30 so that the voltage A1 = 3 kV, the voltage A2 = 6 kV, and the auxiliary voltage ACL = 10 kV. At this time, the voltage A3 = −70 / 7 + 10 = −20 kV, and the potential difference A2-A3 = 14 kV. In this way, the processing of the control unit 32 suppresses the decrease in the potential of the first-stage acceleration electrode 201 due to the switching to the lower acceleration voltage, and the convergent lens formed between the acceleration electrode 104 and the first-stage acceleration electrode 201. It is possible to suppress the decrease in the action of.

電子顕微鏡１は、例えば、加速電極２０１の電位の低下が抑制される最適な、加速電圧ＨＴと、補助電圧ＡＣＬと、の関係を示すテーブルが記憶された記憶装置（図示せず）を有している。制御部３２は、加速電圧ＨＴが変更された場合に、このテーブルに基づいて補助電圧ＡＣＬを設定する。これにより、加速電圧ＨＴの変更された場合に、適切な補助電圧ＡＣＬを加速電圧ＨＴに重畳することができる。 The electron microscope 1 has, for example, a storage device (not shown) in which a table showing the relationship between the acceleration voltage HT and the auxiliary voltage ACL, which is optimal for suppressing the decrease in the potential of the acceleration electrode 201, is stored. ing. The control unit 32 sets the auxiliary voltage ACL based on this table when the acceleration voltage HT is changed. Thereby, when the acceleration voltage HT is changed, an appropriate auxiliary voltage ACL can be superimposed on the acceleration voltage HT.

なお、上記では、制御部３２が加速電圧ＨＴの変更に応じて補助電圧ＡＣＬを設定する場合について説明したが、ユーザーが操作部（図示せず）を介して補助電圧ＡＣＬの大きさを設定することで、制御部３２が設定された補助電圧ＡＣＬを加速電圧ＨＴに重畳する処理を行ってもよい。すなわち、この場合、ユーザーが補助電圧ＡＣＬを任意の大きさに設定できる。 In the above, the case where the control unit 32 sets the auxiliary voltage ACL according to the change of the acceleration voltage HT has been described, but the user sets the size of the auxiliary voltage ACL via the operation unit (not shown). As a result, the control unit 32 may perform a process of superimposing the set auxiliary voltage ACL on the acceleration voltage HT. That is, in this case, the user can set the auxiliary voltage ACL to an arbitrary size.

４． 特徴
電子顕微鏡１は、例えば、以下の特徴を有する。 4. Features The electron microscope 1 has the following features, for example.

電子顕微鏡１は、エミッタ１００と、エミッタ１００から電子を引き出す引き出し電極１０２と、引き出し電極１０２の後段に配置され、エミッタ１００から引き出された電子線を加速させる加速電極１０４と、加速電極１０４の後段に配置され、複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６を備える加速管２０と、加速電圧ＨＴを発生させる高圧電源３００と、補助電圧ＡＣＬを発生させる補助電圧電源３０６と、加速電圧ＨＴと補助電圧ＡＣＬとが重畳された入力電圧を分圧して、複数の加速電極２０１，２０２，２０３，２０４，２０５，２０６の各々に印加する複数の抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７と、を含む。 The electron microscope 1 is arranged after the emitter 100, the extraction electrode 102 for drawing electrons from the emitter 100, and the acceleration electrode 104 for accelerating the electron beam drawn from the emitter 100, and the rear stage of the acceleration electrode 104. An acceleration tube 20 having a plurality of acceleration electrodes 201, 202, 203, 204, 205, 206, a high voltage power supply 300 for generating an acceleration voltage HT, an auxiliary voltage power supply 306 for generating an auxiliary voltage ACL, and acceleration. Multiple resistance elements 211,222,223,224, which divide the input voltage on which the voltage HT and the auxiliary voltage ACL are superimposed and apply it to each of the plurality of acceleration electrodes 201, 202, 203, 204, 205, 206. 225, 226, 227 and the like.

そのため、電子顕微鏡１では、複数の抵抗素子２２１，２２２，２２３，２２４，２２５，２２６，２２７の入力電圧を加速電圧ＨＴと補助電圧ＡＣＬとが重畳された電圧とすることができる。そのため、補助電圧ＡＣＬを制御することによって、加速電極１０４と初段の加速電極２０１との間の電位差Ａ２－Ａ３を制御することができる。これにより、
加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用を制御できる。したがって、電子顕微鏡１では、例えば、加速電圧ＨＴが変更された場合であっても、加速電圧ＨＴの印加を停止することなく、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用が低下することを抑制できる。 Therefore, in the electron microscope 1, the input voltage of the plurality of resistance elements 221,222,223,224,225,226,227 can be set as the voltage on which the acceleration voltage HT and the auxiliary voltage ACL are superimposed. Therefore, by controlling the auxiliary voltage ACL, the potential difference A2-A3 between the accelerating electrode 104 and the accelerating electrode 201 of the first stage can be controlled. This will result in
The action of the convergent lens formed between the accelerating electrode 104 and the accelerating electrode 201 of the first stage can be controlled. Therefore, in the electron microscope 1, for example, even when the acceleration voltage HT is changed, the convergence formed between the acceleration electrode 104 and the first-stage acceleration electrode 201 without stopping the application of the acceleration voltage HT. It is possible to suppress the decrease in the action of the lens.

さらに、電子顕微鏡１では、例えば上記の短絡機構を設ける場合と比べて、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用を細かく制御できる。これにより、クロスオーバー位置を精度よく調整することができる。 Further, in the electron microscope 1, the action of the convergent lens formed between the accelerating electrode 104 and the first-stage accelerating electrode 201 can be finely controlled as compared with the case where the short-circuit mechanism is provided, for example. As a result, the crossover position can be adjusted with high accuracy.

電子顕微鏡１は、補助電圧電源３０６を制御する制御部３２を含み、制御部３２は、加速電圧ＨＴの変更に応じて補助電圧ＡＣＬを設定し、加速電圧ＨＴに補助電圧ＡＣＬを重畳して分圧用回路２２０の入力電圧とする処理を行う。そのため、電子顕微鏡１では、加速電圧ＨＴが変更された場合であっても、適切な補助電圧ＡＣＬを設定できる。したがって、例えば、高加速電圧から低加速電圧に切り替えた場合であっても、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用が低下することを抑制できる。 The electron microscope 1 includes a control unit 32 that controls the auxiliary voltage power supply 306, and the control unit 32 sets the auxiliary voltage ACL according to the change of the acceleration voltage HT, and superimposes the auxiliary voltage ACL on the acceleration voltage HT. The process of using the input voltage of the compression circuit 220 is performed. Therefore, in the electron microscope 1, an appropriate auxiliary voltage ACL can be set even when the acceleration voltage HT is changed. Therefore, for example, even when the high acceleration voltage is switched to the low acceleration voltage, it is possible to suppress the deterioration of the action of the convergent lens formed between the acceleration electrode 104 and the acceleration electrode 201 of the first stage.

本実施形態に係る電子顕微鏡１の制御方法は、加速電圧ＨＴを変更する工程と、加速電圧ＨＴの変更に応じて補助電圧ＡＣＬを設定し、加速電圧ＨＴに補助電圧ＡＣＬを重畳して入力電圧とする工程と、を含む。そのため、加速電圧が変更された場合であっても、加速電圧ＨＴの印加を停止することなく、加速電極１０４と初段の加速電極２０１との間に形成される収束レンズの作用が低下することを抑制できる。 In the control method of the electron microscope 1 according to the present embodiment, the auxiliary voltage ACL is set according to the step of changing the acceleration voltage HT and the change of the acceleration voltage HT, and the auxiliary voltage ACL is superimposed on the acceleration voltage HT to input the input voltage. And the process of Therefore, even when the acceleration voltage is changed, the action of the convergent lens formed between the acceleration electrode 104 and the acceleration electrode 201 of the first stage is reduced without stopping the application of the acceleration voltage HT. Can be suppressed.

なお、上記では、電子顕微鏡１が透過電子顕微鏡である場合について説明したが、本発明に係る電子顕微鏡は、走査電子顕微鏡（scanning electron microscope、ＳＥＭ）であってもよい。 Although the case where the electron microscope 1 is a transmission electron microscope has been described above, the electron microscope according to the present invention may be a scanning electron microscope (SEM).

本発明は、実施の形態で説明した構成と実質的に同一の構成（例えば、機能、方法および結果が同一の構成、あるいは目的及び効果が同一の構成）を含む。また、本発明は、実施の形態で説明した構成の本質的でない部分を置き換えた構成を含む。また、本発明は、実施の形態で説明した構成と同一の作用効果を奏する構成又は同一の目的を達成することができる構成を含む。また、本発明は、実施の形態で説明した構成に公知技術を付加した構成を含む。 The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. Further, the present invention includes a configuration having the same effect as the configuration described in the embodiment or a configuration capable of achieving the same object. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

１…電子顕微鏡、１０…電子銃、２０…加速管、３０…電源部、３２…制御部、４０…収束レンズ、５０…試料ホルダー、６０…対物レンズ、７０…中間レンズ、８０…投影レンズ、９０…検出器、１００…エミッタ、１０２…引き出し電極、１０４…加速電極、２０１…加速電極、２０２…加速電極、２０３…加速電極、２０４…加速電極、２０５…加速電極、２０６…加速電極、２１０…碍子、２２０…分圧用回路、２２１…抵抗素子、２２２…抵抗素子、２２３…抵抗素子、２２４…抵抗素子、２２５…抵抗素子、２２６…抵抗素子、２２７…抵抗素子、２３０…筐体、３００…高圧電源、３０１…フィラメント電源、３０２…引き出し電極用電源、３０４…加速電極用電源、３０６…補助電圧電源 1 ... Electron microscope, 10 ... Electron gun, 20 ... Acceleration tube, 30 ... Power supply unit, 32 ... Control unit, 40 ... Convergent lens, 50 ... Sample holder, 60 ... Objective lens, 70 ... Intermediate lens, 80 ... Projection lens, 90 ... detector, 100 ... emitter, 102 ... extraction electrode, 104 ... acceleration electrode, 201 ... acceleration electrode, 202 ... acceleration electrode, 203 ... acceleration electrode, 204 ... acceleration electrode, 205 ... acceleration electrode, 206 ... acceleration electrode, 210 ... 碍, 220 ... voltage dividing circuit, 221 ... resistance element, 222 ... resistance element, 223 ... resistance element, 224 ... resistance element, 225 ... resistance element, 226 ... resistance element, 227 ... resistance element, 230 ... housing, 300 ... High-voltage power supply, 301 ... Filament power supply, 302 ... Lead-out electrode power supply, 304 ... Acceleration electrode power supply, 306 ... Auxiliary voltage power supply

Claims (5)

エミッタと、
前記エミッタから電子を引き出す引き出し電極と、
前記引き出し電極の後段に配置され、前記エミッタから引き出された電子線を加速させる第１加速電極と、
前記第１加速電極の後段に配置され、複数の第２加速電極を備える加速管と、
加速電圧を発生させる加速電圧電源と、
前記第１加速電極に電圧を印加する加速電極用電源と、
補助電圧を発生させる補助電圧電源と、
前記加速電圧と前記補助電圧とが重畳された入力電圧を分圧して、前記複数の第２加速電極の各々に印加する複数の分圧用抵抗と、
を含み、
前記加速電極用電源で前記第１加速電極の電位を制御し、前記補助電圧電源で前記複数の第２加速電極のうちの１つの第２加速電極の電位を制御することによって、前記第１加速電極と前記１つの第２加速電極との間のレンズ作用を制御する、電子顕微鏡。 Emitter and
An extraction electrode that draws electrons from the emitter and
A first accelerating electrode, which is arranged after the extraction electrode and accelerates the electron beam drawn from the emitter,
An accelerating tube arranged after the first accelerating electrode and having a plurality of second accelerating electrodes,
Acceleration voltage power supply that generates acceleration voltage,
A power supply for an accelerating electrode that applies a voltage to the first accelerating electrode,
Auxiliary voltage power supply that generates auxiliary voltage and
A plurality of voltage dividing resistors that divide the input voltage on which the acceleration voltage and the auxiliary voltage are superimposed and apply it to each of the plurality of second acceleration electrodes.
Including
The first acceleration is performed by controlling the potential of the first acceleration electrode with the power supply for the acceleration electrode and controlling the potential of the second acceleration electrode of one of the plurality of second acceleration electrodes with the auxiliary voltage power supply. An electron microscope that controls the lens action between the electrode and the one second accelerating electrode . 請求項１において、
前記引き出し電極に電圧を印加する引き出し電極用電源を含み、
前記引き出し電極用電源で前記引き出し電極の電位を制御し、前記加速電極用電源で前記第１加速電極の電位を制御することによって、前記引き出し電極と前記第１加速電極との間のレンズ作用を制御する、電子顕微鏡。 In claim 1,
A power supply for the lead-out electrode that applies a voltage to the lead-out electrode is included.
By controlling the potential of the extraction electrode with the power supply for the extraction electrode and controlling the potential of the first acceleration electrode with the power supply for the acceleration electrode, the lens action between the extraction electrode and the first acceleration electrode can be obtained. An electron microscope to control . 請求項１または２において、
前記加速電圧は、可変である、電子顕微鏡。 In claim 1 or 2,
The acceleration voltage is variable, an electron microscope. 請求項１ないし３のいずれか１項において、
前記補助電圧電源を制御する制御部を含み、
前記制御部は、前記加速電圧の変更に応じて前記補助電圧を設定し、前記加速電圧に前記補助電圧を重畳して前記入力電圧とする処理を行う、電子顕微鏡。 In any one of claims 1 to 3,
A control unit that controls the auxiliary voltage power supply is included.
The control unit sets the auxiliary voltage in response to a change in the acceleration voltage, and superimposes the auxiliary voltage on the acceleration voltage to obtain the input voltage. エミッタと、
前記エミッタから電子を引き出す引き出し電極と、
前記引き出し電極の後段に配置され、前記エミッタから引き出された電子線を加速させる第１加速電極と、
前記第１加速電極の後段に配置され、複数の第２加速電極を備える加速管と、
加速電圧を発生させる加速電圧電源と、
前記引き出し電極に電圧を印加する引き出し電極用電源と、
前記第１加速電極に電圧を印加する加速電極用電源と、
補助電圧を発生させる補助電圧電源と、
前記加速電圧と前記補助電圧とが重畳された入力電圧を分圧して前記複数の第２加速電極の各々に印加する複数の分圧用抵抗と、を含む電子顕微鏡の制御方法であって、
前記引き出し電極用電源で前記引き出し電極の電位を制御し、前記加速電極用電源で前記第１加速電極の電位を制御することによって、前記引き出し電極と前記第１加速電極の間のレンズ作用を制御する工程と、
前記加速電圧を変更する工程と、
前記加速電圧の変更に応じて前記補助電圧電源を制御することによって前記複数の第２加速電極のうちの１つの第２加速電極の電位を制御して、前記第１加速電極と前記１つの第２加速電極との間のレンズ作用を制御する工程と、
を含む、電子顕微鏡の制御方法。 Emitter and
An extraction electrode that draws electrons from the emitter and
A first accelerating electrode, which is arranged after the extraction electrode and accelerates the electron beam drawn from the emitter,
An accelerating tube arranged after the first accelerating electrode and having a plurality of second accelerating electrodes,
Acceleration voltage power supply that generates acceleration voltage,
A power supply for the lead-out electrode that applies a voltage to the lead-out electrode,
A power supply for an accelerating electrode that applies a voltage to the first accelerating electrode,
Auxiliary voltage power supply that generates auxiliary voltage and
It is a control method of an electron microscope including a plurality of voltage dividing resistors that divide an input voltage in which the acceleration voltage and the auxiliary voltage are superimposed and apply it to each of the plurality of second acceleration electrodes.
By controlling the potential of the extraction electrode with the power supply for the extraction electrode and controlling the potential of the first acceleration electrode with the power supply for the acceleration electrode, the lens action between the extraction electrode and the first acceleration electrode is controlled. And the process to do
The process of changing the acceleration voltage and
By controlling the auxiliary voltage power supply in response to the change in the acceleration voltage, the potential of the second acceleration electrode of the plurality of second acceleration electrodes is controlled, and the first acceleration electrode and the one first acceleration electrode are controlled. 2 The process of controlling the lens action between the accelerating electrode and
How to control an electron microscope, including .
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